Courtesy PhotoHeath Ledger, left, and Lily Cole shown in a scene from, "The Imaginarium of Doctor Parnassus."There's no debating Terry Gilliam's ambition. His films are notorious for their visual jabberwocky and surrealist narratives, and ever since 1975's "Monty Python and the Holy Grail," we have come to expect oddity from him.
But that oddity is a heavy weight around "The Imaginarium of Doctor Parnassus," which plays like a string of tangents, the plot kicked and fumbled and tossed around like a rugby ball. Similar to my experiences watching rugby, I don't know the rules, but I'm entertained by the film's color and movement. Effort and repeated viewing might lead to clarity.

The question is whether "Parnassus" deserves such mental exertion. It's an entertainingly jumbled mess, the art direction exploding with untethered creativity, the performances inspired, bordering on manic. But we grow weary as the run time stretches, the bizarre imagery and obtuse characters testing our patience.

The film is famous for featuring Heath Ledger's last role. He died during principal photography, and Gilliam recruited Johnny Depp, Jude Law and Colin Farrell to complete the project, portraying his character in alternate realities. Judging the final product, it's difficult to tell if Ledger's passing contributed to the fractured film, or if its cut-and-paste style was part of Gilliam's inscrutable plan.

At film's core is a group of ragamuffin traveling troubadours, led by Dr. Parnassus (Christopher Plummer), a doddering old depressive drunk who wagered with the devil, here dubbed Mr. Nick (Tom Waits), and won his immortality. He's accompanied by his apple-cheeked teenage daughter Valentina (Lily Cole), the actor Anton (Andrew Garfield) and the diminutive Percy (Verne Troyer) as they roll through modern urban cities in a massive, rickety horse-drawn contraption with a fold-out stage.

In performance, Parnassus goes into a meditative trance, allowing passersby to enter the strangescapes of his mind via a mirror. Inside, it resembles a hypnagogic Middle Earth, or a hallucinogenic Candy Land; logic and the laws of physics don't necessarily apply. Joining the carnies is Tony (Ledger), a no-goodnik who feigns amnesia to hide the fact that he's on the run because of his morally corrupt deeds. He's the right man to aid Parnassus in the collection of mortal souls, many of them crude and clueless, crocked on booze or consumers of superficial culture.

The whys of this fable aren't as important to Gilliam as the enveloping weirdness, which provides some laughs and oodles of eye candy, but struggles to sustain a thematic thread. He builds a myth like a professional, and gross deduction reveals an elusive wisp of an idea: how storytellers create and proliferate truth. You have to dig through piles of peculiarity to come to this small conclusion, however, and be up to the task.